AIR FORCE ACADEMY, Colo. — A change in San Diego State’s defensive scheme helped the Aztecs slow down Air Force’s run-heavy offense. Matt Araiza kicked two field goals, Kaegun Williams and Chance Bell ran for touchdowns and No. 22 San Diego State withstood Air Force’s comeback bid to win 20-14 on Saturday night. The Aztecs kept Air Force’s top-ranked running attack in check by frequently using a fourth linebacker instead of a defensive back. “Everybody knows what they do,” Aztecs linebacker Michael Shawfroft said.